/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.linkis.engineconnplugin.flink.client.sql.operation.impl;

import org.apache.linkis.engineconnplugin.flink.client.config.Environment;
import org.apache.linkis.engineconnplugin.flink.client.context.ExecutionContext;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.NonJobOperation;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.OperationUtil;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.result.ResultSet;
import org.apache.linkis.engineconnplugin.flink.context.FlinkEngineConnContext;
import org.apache.linkis.engineconnplugin.flink.exception.SqlExecutionException;

import org.apache.flink.table.client.config.entries.TableEntry;
import org.apache.flink.table.client.config.entries.ViewEntry;

/** Operation for DROP VIEW command. */
public class DropViewOperation implements NonJobOperation {
    private final FlinkEngineConnContext context;
    private final String viewName;
    private final boolean ifExists;

    public DropViewOperation(FlinkEngineConnContext context, String viewName, boolean ifExists) {
        this.context = context;
        this.viewName = viewName;
        this.ifExists = ifExists;
    }

    @Override
    public ResultSet execute() throws SqlExecutionException {
        Environment env = context.getExecutionContext().getEnvironment();
        TableEntry tableEntry = env.getTables().get(viewName);
        if (!(tableEntry instanceof ViewEntry) && !ifExists) {
            throw new SqlExecutionException(
                    "'" + viewName + "' does not exist in the current session.");
        }

        // Here we rebuild the ExecutionContext because we want to ensure that all the remaining
        // views can work fine.
        // Assume the case:
        //   view1=select 1;
        //   view2=select * from view1;
        // If we delete view1 successfully, then query view2 will throw exception because view1 does
        // not exist. we want
        // all the remaining views are OK, so do the ExecutionContext rebuilding to avoid breaking
        // the view dependency.
        Environment newEnv = env.clone();
        if (newEnv.getTables().remove(viewName) != null) {
            ExecutionContext oldExecutionContext = context.getExecutionContext();
            oldExecutionContext.wrapClassLoader(tableEnv -> tableEnv.dropTemporaryView(viewName));
            // Renew the ExecutionContext.
            ExecutionContext.Builder builder =
                    context.newExecutionContextBuilder(
                                    context.getEnvironmentContext().getDefaultEnv())
                            .env(newEnv)
                            .sessionState(context.getExecutionContext().getSessionState());
            context.setExecutionContext(
                    context.getExecutionContext().cloneExecutionContext(builder));
        }

        return OperationUtil.OK;
    }
}
